Valve apparatus

ABSTRACT

A valve apparatus [ 11 ] for connection to a tank or pipe, the valve apparatus [ 11 ] comprises a housing [ 12 ], a first opening [ 176   a ] and a second opening [ 177   a ] communicating with respective first conduit [ 16 ] and second conduit [ 17 ] each for providing ingress and egress of fluid into and out of the housing [ 11 ] through the first opening [ 176   a ] and the second opening [ 177   a ], and discrete first and second valve means or valves [ 14; 15 ] which are spaced apart from one another, the first and second valve means or valves [ 14; 15 ] selectively controlling fluid flow between the first and second conduits [ 16; 17 ], wherein, in use, the principal flow axes along the first conduit [ 16 ] and second conduit [ 17 ] are parallel and opposed, the first valve means or valve [ 14 ]is configured to open when the pressure in the first conduit [ 16 ] is greater than a first pressure and the second valve means or valve [ 17 ] is configured to open when the pressure in the first conduit [ 16 ] is less than the first pressure.

This invention relates generally to valve apparatus. More specifically,although not exclusively, this invention relates to pressure and vacuumrelief valve apparatus.

Numerous industries, for example the petrochemical industry and thedistillery industry, require the prevention of the build-up of excessivepositive or negative pressures within a pipe or container (for example atank, storage tank or storage vessel). Accordingly, it is known toprovide valve means on such pipes or containers, where the valve meansis configured to allow the flow of fluid out of the pipe or container ifthe pressure of the fluid therewithin exceeds a pre-set maximum value orto allow a flow of fluid in to the pipe or container if the pressure ofthe fluid therewithin is less than a pre-set minimum value. If fluid isallowed to leave the pipe or container that is called an out-breathingmode, if fluid is allowed to enter the pipe or container that is knownas an inbreathing mode. Of course, out-breathed fluids will comprise thefluids contained within the pipe or container whereas in-breathed fluidswill comprise those fluids without the pipe or container and willtypically be air (or an inert gas).

Furthermore, a vapour cloud may form a combustible or explosiveatmosphere in the vicinity of industrial equipment. Such a combustibleor explosive vapour cloud may be generated, at least in part, by fluidvented through valve means as described above. An ignition of thisvapour cloud (due to sparks, lightning, static electricity etc.) willinitiate an atmospheric deflagration or a vapour cloud explosion. Wherethe vapour cloud is in the vicinity of valve means as described above,and those valve means are in an open condition, the deflagration orexplosion may enter the pipe or container on which the valve means isdisposed. The contents of the pipe or container may then become subjectto deflagration or explosion and/or the contents of further piping orcontainers connected thereto, for example in a downstream (in thedirection of flame propagation) tank system. Typical installations inwhich such events may be encountered include tank venting systems, e.g.storage tanks.

Flame arresters represent one solution to the challenge of mitigatingthe risk of deflagration and/or explosion propagation. A flame arrestercomprises a flame arrester element which may be constructed from aporous matrix, for example a crimped ribbon, which allows gas or vapourto flow through the flame arrester. The flame arrester element isdesigned principally to prevent flame transmission in the event of anexplosion.

A valve apparatus may be integrated with a flame arrester. The valveapparatus may comprise a housing, a flame arrester element, a pressurerelief valve and a vacuum relief valve, where the flame arrester elementis located within the housing. The flame arrester is typically anend-of-line (EOL) device, designed to protect plant and equipment froman externally ignited atmospheric deflagration. The flame arresterelement is designed to prevent a flame front from entering into, andpropagating through, a piping system attachable to the valve apparatus'inlet. The valves control fluid communication between the inlet and anoutlet, wherein the flame arrester element is disposed. The principalflow axis through the inlet is typically perpendicular to the principalflow axis through the outlet.

The flame arrester element is provided on one side of the valveapparatus and is covered by a weather hood designed to protect the flamearrester element from damage from atmospheric contaminants. The pressurerelief valve and vacuum relief valve are biased toward a closedcondition by the mass of the valve plates or pallets of each valve.Accordingly, such a valve apparatus must be installed in a verticalorientation.

Flame arresters can be susceptible to becoming blocked. Such blockagesmay occur in a number of different ways: for example, airborne solidsmay be deposited on the face of the flame arrester element, moisture maycondense and freeze on the flame arrester element surface under theright meteorological conditions, and flame arrester elements may also beattractive for nesting birds and bees/wasps which can cause partial ortotal blockage to the vent system. If a flame arrester becomes evenpartially blocked, the flame arrester flow capacity will be reduced and,in extreme cases, there will be a serious risk of catastrophic damage toequipment (for example, to storage tanks during filling and emptying oras a result of weather changes). Moreover, the pressure drop across theflame arrester will likely increase leading to suboptimal performance.

Accordingly, regular maintenance and inspections are vital to preventblockage of the flame arrester element and to ensure that it operateseffectively under normal flow conditions and also in the event of anexplosion. A common problem experienced with conventional EOL flamearresters, such as that described above, concerns the routinemaintenance and visual inspection of the flame arrester element, whichis hidden from view by the weather hood. This issue is exacerbated whenthe flame arrester is installed at a location significantly elevatedabove ground level, as is common.

An alternative valve apparatus may be integrated with a flame arrestersuch that the valve apparatus is provided with plural flame arresterelements. The alternative valve apparatus includes a housing, a pressurerelief valve and a vacuum relief valve. This valve apparatus includes aninlet, a vacuum relief inlet and an outlet. The vacuum relief valvecontrols fluid communication between the inlet and the vacuum reliefinlet, with a first flame arrester element disposed therewithin. Thepressure relief valve controls fluid communication between the inlet andthe outlet, with a second flame arrester element disposed therewithin. Adrainage outlet including a third flame arrester element is locatedwithin the housing, downstream of the pressure relief valve. Thealternative valve apparatus must also be installed in the verticalorientation, for similar reasons to those discussed in respect of thepreviously described valve apparatus.

The alternative valve apparatus includes a flame arrester element, whichis not visible during use, and consequently this design suffers forreasons similar to those set out in respect of the previously describedvalve apparatus. Furthermore, the provision of plural flame arresterelements provides a relatively more complex design, thereby includingmore components which may be susceptible to failure prior to or duringuse. Moreover, commonly flame arrester elements may be removed formaintenance and/or replacement. Such removal is more complex and timeconsuming where plural flame arrester elements are included instead of asingle flame arrester element.

A further valve apparatus is described in WO93/16310. It will beappreciated that the weight distribution is asymmetrical.

Valve apparatus of the described types are commonly installed at alocation significantly elevated above ground level, as explained above.The balance, weight and/or compactness of such valve apparatus istherefore of vital importance in order that they are suitable forinstallation at such locations. The above described valve apparatus (inparticular the alternative and further valve apparatus) have animbalanced weight distribution (with respect to the inlet) andconsequently installation requires the installer to consider how thevalve apparatus will operate in certain locations (e.g. locationsexposed to strong winds and/or where a pipe connected to the inlet isrelatively long) or may require a stronger mount than might otherwise berequired.

It is therefore a first non-exclusive object of the invention to providea valve apparatus which at least partially mitigates theabove-identified problems and/or has improved performance over prior artvalve apparatus.

Accordingly, a first aspect of the invention provides a valve apparatusfor connection to a pipe or container (e.g. tank, storage tank orstorage vessel), the valve apparatus comprising a housing, a firstopening and a second opening communicating with respective first andsecond conduits each for providing ingress and egress of fluid into andout of the housing through the first opening and the second opening, anddiscrete first and second valve means or valves which are spaced apartfrom one another, the first and second valve means or valves selectivelycontrolling fluid flow between the first and second conduits, wherein,in use, the principal flow axes along the first conduit and secondconduit are parallel and opposed, the first valve means or valve isconfigured to open when the pressure in the first conduit is greaterthan a first pressure and the second valve means or valve is configuredto open when the pressure in the first conduit is less than the firstpressure.

The invention thus provides a valve apparatus in which opening of thefirst and second valve means or valves is entirely independent.Consequently, opening of the first and/or second valve means or valvesis not dependent on the proper functioning of the other valve means orvalve. Therefore, advantageously, if the second valve means or valvefails (for whatever reason) the first valve means or valve will stillfunction and will open if the pressure in the first conduit is greaterthan the first pressure, and vice versa.

One skilled in the art will appreciate that where the first and secondvalve means or valves are described as being discrete this is differentto a valve mechanism in which the valve seat of one valve forms part ofthe valve plate or pallet of another valve (wherein the valves are notdiscrete).

In the valve apparatus according to the first aspect of the invention,when both valve means or valves are in a closed condition fluid may beprevented from flowing between the conduits. When the first valve meansor valve is in an open condition thereby allowing fluid to flow from thefirst conduit to the second conduit the valve apparatus may be in anout-breathing mode or condition. When the second valve means or valve isin an open condition thereby allowing fluid to flow from the secondconduit to the first conduit the valve apparatus may be in anin-breathing mode or condition.

The first and second valve means or valves may be spaced apart from oneanother by any suitable distance. The first valve means or valve maycomprise a first valve member, for example a first valve plate orpallet, e.g. and a first valve seat. The second valve means or valve maycomprise a second valve member, for example a second valve plate orpallet, e.g. and a second valve seat. The first and/or second valveplate or pallet may be configured to provide a fluid tight seal against,respectively, the first and/or second valve seat, for example in aclosed condition or position. The first valve means or valve maycomprise a pressure relief valve. The second valve means or valve maycomprise a vacuum relief valve. The first valve plate or pallet andsecond valve plate or pallet may be substantially parallel to oneanother. The first and second valve plates or pallets may besubstantially coaligned, e.g. substantially coaxial. The first and/orthe second valve plates or pallets may be removably attached to,respectively, the first and second valve seats. The first and secondvalve means or valves (e.g. the first and second valve plates orpallets) may be aligned with one another, for example vertically (e.g.when the valve apparatus is installed at a site of use). The first valvemeans or valve (e.g. the first valve plate or pallet) may comprise acentral axis, for example perpendicular to a major plane of, the firstvalve means or valve (e.g. the first valve plate or pallet). The secondvalve means or valve (e.g. the second valve plate or pallet) maycomprise a central axis, for example perpendicular to a major plane of,the second valve means or valve (e.g. the second valve plate or pallet).The central axes of the first and second valve means or valves (e.g. thefirst and second valve plates or pallets) may be aligned. The firstand/or second conduit may comprise a central axis, for example alongwhich the principal flow axes extend. The central axis of the firstand/or the second valve means or valve (e.g. the first and/or the secondvalve plate or pallet) may be aligned with the central axis of the firstand/or the second conduit. Advantageously, such aligned valve means orvalves and conduits provide a valve apparatus having relatively enhancedweight distribution. Alternatively, the second valve means or valve maybe horizontally displaced from the first valve means or valve. In anembodiment, the second valve means or valve may comprise plural secondvalve plates or pallets. Preferably, the second valve means, e.g. theplural second valve plates or pallets are distributed symmetricallyabout the first valve means or valve.

The valve means or valve set, e.g. the first and/or second valve meansor valve, may be configured to be biased in use toward a closed positionor condition. The bias may be generated by a biasing means or biaser,for example a mass. The mass may be attached to, mounted to, associatedwith and/or comprise the first and/or second valve (e.g. the firstand/or second valve plate or pallet). The first and/or second valveplate or pallet may comprise the mass. Additionally or alternatively,the biasing means or biaser may comprise a resilient biasing means orbiaser, for example one or more springs or resilient elements or members(e.g. a member comprising elastomeric material).

The valve apparatus may comprise a seal or sealing means, for exampleconfigured to seal the valve means or valve set (e.g. to provide a sealbetween the first and/or second valve plate or pallet relative to,respectively, the first and/or second valve seat). The seal or sealingmeans may be configured to provide a fluid tight seal. The seal orsealing means may comprise one or more seals. In embodiments the one ormore seals may comprise one or more air cushion seals. Advantageously,air cushion seals provide tight sealing thereby reducing evaporationlosses and/or emissions through or by the seal. Accordingly, a low rateof leakage is achieved. The one or more seals may comprise a diaphragm,for example at least partially formed from PTFE or FEP.

The valve apparatus may comprise guide means or one or more guides, forexample configured to guide, in use, the valve means or valve set (e.g.the first and/or second valve means or valves). The guide means or oneor more guides may be configured to guide the first and/or second valveplate or pallet relative to its respective valve seat, e.g. thereby toensure a correct seating of the valve(s). The guide means or one or moreguides may comprise one or more cooperating projections and recesses.The, some or each projection may be configured to move within itscooperating recess when the valve means or valve set moves toward oraway from an open and/or closed condition or position (e.g. when atleast one part of the valve means or valve set moves toward or away froman open and/or closed condition or position). In embodiments the firstvalve plate or pallet and/or the second valve plate or pallet maycomprise one, some or all of the one or more projections. In embodimentsthe first valve plate or pallet and/or the second valve plate or palletmay comprise one, some or all of the one or more recesses. The recessesmay comprise a corresponding shape to that of the projections, innegative. The projections may be configured to slidably engage in orwith the recesses, in use. The guide means or one or more guides maycomprise outer guidance for the first and/or second valve plate(s) orpallet(s) and/or one or more central stabilizing stem(s), for example toprovide alignment of the plate(s) or pallet(s) and to ensure tightsealing.

In this way the or each valve plate or pallet remains correctly alignedwith respect to its respective valve seat, in use, and will be properlyand tightly sealed thereagainst when in a closed position or condition.

The second conduit may be at least partially defined between the firstconduit and the housing. The second conduit may surround (for example atleast partially) the first conduit or an end thereof, e.g. may entirelysurround the first conduit or an end thereof. The first and secondconduits may be coaxial or may be eccentrically arranged.

The housing may be configured, in use, to cover the valve means or valveset (for example the first and second valve means or valves).Advantageously, the valve means or valve set (e.g. the first and secondvalve means or valves) is therefore protected from environmentalconditions such as precipitation and/or wind. Accordingly, the valvemeans or valve set (for example the first and second valve means orvalves) may function more reliably, e.g. in use. Moreover, the valvemeans or valve set (e.g. the first and second valve means or valves) isin fluid communication with the atmosphere around the valve apparatus.Therefore, the valve means or valve set (e.g. the first and second valvemeans or valves) functions reliably, in use.

The housing may comprise an end wall or portion, for example an openableor removable end wall or portion. The end wall or portion may besubstantially perpendicular to the principal flow axes. The housing maycomprise one or more side walls, for example surrounding and/or at leastpartially defining the second conduit. The side walls may extend atleast partially around the first conduit, e.g. around an end thereof.The end wall or portion may be removably attached to the side walls orwalls, for example by fixing means or fixings. The end portion maycomprise a portion of the end wall, for example a removable portion ofthe end wall. The end portion may be removably attached to the fixed ornon-removable portion of the end wall, for example by fixing means orfixings. The end wall or portion may comprise a greater area (e.g. havegreater dimensions) than do the first and/or second valve plate orpallet (where provided). The fixing means or fixings may comprise one ormore bolts and/or one or more flanges, for example extending from theend wall and/or the side wall or walls. The end wall (where provided) orportion may comprise a lifting eye or lug or ring nut or any othersuitable attachment.

The end wall or portion that may be flat or in a dished-end form e.g.dome, may be configured (e.g. hinged lid) to automatically open as apressure in the first conduit reaches a pre-set/pre-determined value ordangerous level for example due to some valve malfunctions or due to theblockage of flame arrester element or in an emergency case.Advantageously, the valve apparatus may operate as an emergency vent oremergency pressure relief device/valve to protect equipment, storagetanks or containers from overpressure damage.

Advantageously, removal or opening of the end wall or the removableportion thereof (where provided) allows rapid and ready access to thefirst and second valve plates or pallets, e.g. for visual inspectionthereof. Consequently, the first and second valve plates or pallets maybe readily and regularly inspected, for example for damage, and may bereplaced when they are determined to no longer be fit for purpose.

The housing may comprise an interior chamber. Said valve means or valveset (e.g. the first and second valve means or valves) may be configuredto allow fluid communication between the first conduit and the interiorchamber. The valve means or valve set (e.g. the second valve means orvalve) may be configured to allow fluid to flow, in use, from theinterior chamber to the first conduit, e.g. when the pressure in thefirst conduit is less than the first pressure. The valve means or valveset (e.g. the first valve means or valve) may be configured to allowfluid to flow, in use, from the first conduit to the interior chamber,e.g. when the pressure in the first conduit is greater than the firstpressure.

A second aspect of the invention provides a flame arrester comprising afirst conduit for fluid flow, a housing, a flame arrester element andvalve means or valve set, where the first conduit extends into thehousing and the flame arrester element at least partially surrounds, andpreferably completely surrounds, the first conduit, the flame arresterelement extending between the first conduit and the housing, whereinsaid valve means or valve set is configured to allow a flow of fluid, inuse, from the first conduit into the housing when the pressure in thefirst conduit is greater than a first pressure and from the housing intothe first conduit when the pressure in the first conduit is less thanthe first pressure.

There is thus provided a flame arrester that is capable of allowing anincrease or a decrease of pressure within the first conduit, therebymitigating against potentially dangerous high or low pressurestherewithin. Furthermore, the arrangement of the flame arrester elementwith respect to the first conduit provides for an even distribution ofweight within the flame arrester. Advantageously, the flame arrester istherefore relatively stable when installed at the end of a pipe and/orat height. The valve means or valve set may comprise a pressure-reliefvalve and a vacuum-relief valve which are discrete. The pressure reliefvalve and vacuum relief valve will preferably be coaxially located.Alternatively, the pressure-relief valve (or vacuum-relief valve) willbe located about the vacuum-relief valve (or pressure-relief valve).

The flame arrester element may be attached or attachable (e.g.removably) to the first conduit and/or the housing.

The flame arrester according to the second aspect of the invention maycomprise a second conduit, for example which may be defined between thehousing and the first conduit. The second conduit may surround the firstconduit, e.g. entirely or partially surround the first conduit. Thesecond conduit may be coaxial with the first conduit. Alternatively, thesecond conduit may be positioned eccentrically, e.g. non-axially alignedwith the first conduit. The first conduit may have a principal flow axisextending therealong and/or the second conduit may have a principal flowaxis extending therealong. The principal flow axes may be parallel, forexample substantially parallel, to one another. The principal flow axesmay be opposed, e.g. in opposite directions. The principal flow axisextending along the second conduit may extend through the flame arresterelement. The valve means or valve set may comprise first and secondvalve means or valves, for example separate or discrete valve means orvalves. The first and second valve means or valves may be configured toselectively open and close fluid communication between the first conduitand the second conduit or the flame arrester element. In use, the firstvalve means or valve may be configured to open when the pressure in thefirst conduit is greater than a first pressure. In use, the second valvemeans or valve may be configured to open when the pressure in the firstconduit is less than the first pressure.

The first pressure may comprise a relatively high-pressure value. Thesecond valve means or valve may be configured to open when the pressurein the first conduit is less than a second pressure. The second pressuremay be less than the first pressure. The second pressure may comprise arelatively low-pressure value.

The first conduit may comprise, as the first opening, an outlet (e.g.when the valve apparatus is in an in-breathing mode), for example at anend thereof. The second conduit may comprise, as the second opening, aninlet (e.g. when the valve apparatus is in an in-breathing mode), forexample at an end thereof. As will be readily understood, in anin-breathing mode fluid will flow through the second conduit and to thefirst conduit. At or adjacent its inlet the second conduit may have atotal cross-sectional area of flow (e.g. a net free area of flow, forexample an annular cross-sectional area) which may be between about 1.5and about 3 times the cross-sectional area of the first conduit at oradjacent its outlet. The above-described cross-sectional areas may beperpendicular to the principal flow axes.

The first conduit may comprise a first end, e.g. and a second end. In anout-breathing mode the first end may provide, as the first opening, aninlet of the valve apparatus (or flame arrester), for example and thesecond opening may provide an outlet of the valve apparatus (or flamearrester). In an in-breathing mode the first end may provide, as thefirst opening, an outlet of the valve apparatus (or flame arrester), forexample and the second opening may provide an inlet of the valveapparatus (or flame arrester). The first conduit may comprise a conduitwall. The first conduit may have a substantially constant cross-sectionalong at least a portion of its length. The first conduit may compriseany suitable cross-sectional shape, for example a circle, oval, ellipse,rectangle, etc.

The first conduit may comprise attachment means or an attachment, e.g.for attachment to a site of use (where the site of use may comprise acontainer, tank, storage tank, storage vessel, pipe or a furtherconduit). The second conduit and/or the housing may comprise attachmentmeans or an attachment, e.g. for attachment to the or a flame arresterelement (where provided) and/or a support structure for a flame arresterelement (such as a flame arrester element ring) and/or a supportstructure for a fluid permeable screen (for example a net, gauze or meshor a perforated plate). The attachment means or attachment may belocated at or adjacent the first end of the first conduit. Theattachment means or attachment may comprise one or more securement meansor securements, e.g. one or more bolts or screws. The attachment meansor attachment may comprise one or more flanges, for example one or moreflanges extending from or at least partially about the first conduitand/or the second conduit and/or the housing.

Provision of attachment means or an attachment allows the valveapparatus to be removably attached to a site of use, for example to acontainer, tank, storage tank, storage vessel, pipe or further conduit.Advantageously, the valve apparatus may be removably attached to a flamearrester element or to a structure containing or configured to retain aflame arrester element (for example a flame arrester element ring). Thevalve apparatus may therefore be reliably and rapidly replaced if it isfound to be unsuitable for use, for example if it is damaged, blocked orotherwise provides vacuum and/or pressure relief at unsuitable pressuresfor the application to which it is intended. Moreover, the valveapparatus may be reliably and rapidly replaced by an end wall or anotherconduit if the configuration of the structure is altered. Moreover, theor a flame arrester element (where provided) may be readily removed orreplaced.

In embodiments of the flame arrester the first valve plate or pallet maycomprise the second valve plate or pallet, for example and the secondvalve seat.

The first valve means or valve may be relatively nearer to the first endof the first conduit than is the second valve means or valve, forexample when both valve means or valves are in a closed position orcondition. Alternatively, the second valve means or valve may berelatively nearer to the first end of the first conduit than is thefirst valve means or valve, for example when both valve means or valvesare in a closed position or condition.

The valve apparatus (or flame arrester) may comprise an extension, e.g.which may comprise the second end of first conduit or may extend from orbe attached or attachable to the second end of the first conduit. Theextension may be configured to define a flow path between the firstconduit and one of the first and second valve means or valves, forexample where the flow path bypasses the other of the first and secondvalve means or valves.

The extension may extend beyond the flame arrester element (whereprovided). The valve means or valve set (e.g. the first valve means orvalve) may be located or mounted to or attached at or adjacent or to theextension. The first valve seat (where provided) may comprise a portionof the extension, e.g. an end portion of the extension, and/or may beaffixed to the end of the extension.

The extension may comprise first and second extensions. The first valvemeans or valve may be mounted or attached to the first extension, e.g.to an end of the first extension. The second valve means or valve may bemounted or attached to the second extension. The second extension may beconcentric and/or coaxial and/or external to the first extension. Thesecond extension may extend from the first extension, for example froman outer surface thereof. The second extension may surround (e.g. atleast partially) the first extension. The first extension may comprise afirst extension wall. One or more apertures may be provided in the firstextension, e.g. through the first extension wall. The second extensionmay comprise a second extension wall. One or more apertures may beprovided in the second extension, e.g. through the second extensionwall.

The second conduit and/or the housing may comprise cleaning means e.g. acleaning nozzle. Cleaning nozzles may be distributed (each at same ordifferent angles and at distinct locations) on a wall of the secondconduit and/or the housing. Nozzles preferably located above the flamearrester element at a site of use may be arranged to discharge acleaning liquid or compressed gas. A cleaning liquid will clean theflame arrester element.

Advantageously, cleaning nozzles provide an in-situ cleaning means andmake maintenance easy. Accordingly the valve apparatus will workefficiently with a less maintenance frequency.

A further aspect of the invention provides valve apparatus or a flamearrester (for example as set out above), comprising a housing having anend wall, the end wall is openable when the pressure within the housingreaches a threshold value. Advantageously, such an end wall will providean emergency pressure relief valve.

A further aspect of the invention provides a flame arrester comprising avalve apparatus as described above. The flame arrester may comprise aflame arrester element, for example located at least partially in oradjacent the second conduit. The flame arrester may comprise a housing,for example into which the first conduit extends. The second conduit maybe defined between the first conduit and the housing. The second conduitmay surround the first conduit, e.g. entirely or partially surround thefirst conduit. The second conduit may be coaxial with the first conduit.Alternatively, the second conduit may be positioned eccentrically, e.g.non-axially aligned with the first conduit. The flame arrester elementmay surround (for example at least partially) the first conduit.

The valve apparatus may comprise a flame arrester element, for examplelocated at least partially in or adjacent the second conduit. The flamearrester element may surround (e.g. at least partially) the firstconduit. The flame arrester element may extend radially from the firstconduit. The flame arrester element may be located substantiallysymmetrically around the first conduit.

The flame arrester element (where provided) may be attached orattachable, e.g. removably attached or attachable, to the valveapparatus. Attachment (e.g. removable attachment) may be affected by useof one or more fixations, for example nuts and bolts and the like.Advantageously, provision of a removable flame arrester element allowsthe flame arrester element to be readily and rapidly removed, forexample for replacement or maintenance such as inspection and/orcleaning. Furthermore, the valve apparatus may hence be used inapparatus other than a flame arrester.

Alternatively, the flame arrester element may be securely attached withthe valve apparatus for example through flange connection. That is, thevalve apparatus comprises the valve means or valves (the upper part ofthe valve apparatus) and the flame arrester or flame arrester element(the lower part of the valve apparatus). The valve means or valves aresecurely attached/fixed through flanges and they are easily separatedfrom each other.

In embodiments, the valve apparatus may comprise a fluid permeablescreen, for example a net, gauze or mesh or a perforated plate. Thefluid permeable screen may be arranged to prevent ingress of objects andorganisms (e.g. birds or insects) into the valve apparatus. Where aflame arrester element is provided a fluid-permeable screen may not berequired.

In embodiments, the first and/or second valve means or valve(s), or anycomponent part thereof, may be removably attached to the valve apparatusor flame arrester. For example, the first and/or second valve member(where provided) may be removably attached to the valve apparatus orflame arrester. In this way, the first and/or second valve means orvalve(s), or any component part thereof, may be readily and rapidlyremoved from the valve apparatus or flame arrester, for example in orderto effect replacement or maintenance thereof. Such ease of maintenanceor replacement provides the valve apparatus or flame arrester with anenhanced useable lifetime relative to valve apparatus or flame arrestersabsent such removably attached components.

The valve apparatus may comprise a partition or wall, e.g. configured toseparate or partition a volume within the housing. The partition or wallmay be configured to define a first chamber, e.g. within the housing.The first chamber may be defined between an end wall of the housing andthe partition or wall. The partition or wall may extend between thefirst conduit (for example the second extension, where present) and thehousing. The partition or wall may surround, e.g. entirely or partially,the first conduit (for example the second extension, where present). Thepartition or wall may extend around the periphery of the first conduit(for example the second extension). The partition or wall may provide afluid tight seal between the first conduit (e.g. the second extension)and the housing.

The valve apparatus may comprise a bypass conduit, for example locatedwithin the housing. The bypass conduit may be in or allow fluidcommunication with the first conduit and/or the first chamber, forexample when the valve means or valve set (e.g. first and/or secondvalves, where present) is in a closed or open condition or position. Thebypass conduit may provide a bypass for fluid flow past the valve meansor valve set, e.g. past at least part of the valve means or valve set(for example past the first and/or second valves, where present). Thebypass conduit may be located on a downstream (when the apparatus and/orflame arrester is in an out-breathing mode) side of the first valve, forexample and upstream of the flame arrester element (where provided). Thefirst conduit, e.g. first conduit wall, may comprise an apertureconfigured to allow fluid communicating with the first chamber (forexample via the bypass conduit).

The bypass conduit may comprise a pipe or tube, for example extendingbetween the first conduit and the first chamber. The valve apparatus orflame arrester or bypass conduit may comprise a diversion barrier orwall extending between the first conduit and the housing. The bypassconduit may be configured to divert, in use, fluid flow away from thesecond conduit (e.g. away from a portion of the second conduit) and/orthe flame arrester element (e.g. away from a portion of the flamearrester element). The diversion barrier or wall may be configured toocclude a portion, e.g. a minor portion, of the second conduit and/orflame arrester element. The diversion barrier or wall may be configuredto define the bypass conduit, e.g. in concert with at least part of thefirst conduit and/or the housing.

The flame arrester element (where provided) may extend radially from thefirst conduit, e.g. concentrically or eccentrically thereabout. Theflame arrester element may radiate away from the first conduit, eitherorthogonally (for example substantially orthogonally) to the principalaxis of the first conduit or at an angle thereto. In this regard,‘orthogonally’ and ‘substantially orthogonally’ need not have theirstrict mathematical meaning, e.g. the flame arrester element may beinclined at an angle of greater than or less than 90° to the principalflow axis of the first conduit. The flame arrester element may extendfrom the first conduit (e.g. the conduit wall) to the housing (e.g. thehousing side wall).

The flame arrester element may comprise a crimped ribbon, wire meshand/or one or more apertured or perforated plates. The flame arresterelement may be located substantially symmetrically, e.g. symmetrically,about the first conduit. The flame arrester element may comprise a firstmajor surface and, for example a second major surface. The first and/orsecond major surface may be substantially orthogonal to the principalflow axis (where provided) extending along the first conduit. Theextension, where provided, may extend beyond both major surfaces of theflame arrester element.

The housing (where provided), the first conduit, the partition or wall(where provided), the second conduit (where provided) and/or theextension (where provided) may be formed by casting or may be formed byany other suitable technique or method, for example forging and/ormachining techniques such as cutting, drilling, grinding, etc.Advantageously, component parts formed by casting may comprise smootheredges and/or more optimised shapes than do component parts formed fromother techniques. Moreover, forming component parts from casting mayallow the formation of relatively complex shapes which, if formed byother techniques, may otherwise require plural individual componentssubsequently joined together (for example via welding). Consequently,forming component parts by casting may enhance the flow of fluid throughand/or against said component parts relative to non-cast componentparts. Furthermore, reduction of sharp edges and joins and/or moreoptimised shapes may result in relatively reduced friction losses duringfluid flow thereover or thereagainst. In particular, casting can producemore streamlined surfaces than can other methods of manufacture, therebyimproving the flow fluids thereagainst and reducing pressure losseswithin the apparatus. Indeed, the flow pattern and/or flow rate of fluidinto and/or through a valve apparatus or flame arrester utilizingcomponent parts formed by casting may be enhanced relative to usingcomponent parts formed by other techniques.

The flame arrester may comprise an EOL flame arrester. Conventional EOLflame arresters usually protect the flame arrester element fromenvironmental effects by a weather hood which hides the flame arresterelement from visual inspection and routine maintenance. Advantageously,the flame arrester of the invention provides for rapid and easy visualinspection of the flame arrester element. Thereby regular maintenanceand inspection of the flame arrester element (which is vital to preventblockage thereof and to ensure effective flow therethrough, whenrequired) is provided by flame arresters according to the presentinvention.

In embodiments the flame arrester element may be at a lower positionthan is the valve means or valve set (e.g. relatively beneath the valvemeans or valve set), when the flame arrester is installed at a site ofuse. The flame arrester according to the invention may therefore notrequire a weather hood to protect the flame arrester element.Additionally, the flame arrester element may provide a barrier againstingress of inanimate objects and/or organisms (such as birds or insects)into the flame arrester and/or the valve apparatus.

Furthermore, condensate and other detritus may drain from the flamearrester through the flame arrester element (or therearound), forexample via the force of gravity. Advantageously, the flame arrester istherefore less likely to become occluded than are prior art flamearresters. Consequently, a build-up of detritus on the flame arresterelement (which might otherwise prevent or impede the flow of fluidtherethrough) is at least partially mitigated, resulting in an increaseduseful lifetime or maintenance interval of the flame arrester.

Advantageously, the flame arrester element (where provided) in a flamearrester according to the present invention may be visible from groundlevel, thereby reducing maintenance and inspection expenses and at leastpartially mitigating against the provision of non-functional flamearrester elements.

In embodiments the flame arrester element may be securely fixed/attachedto the valve means or valve set through flange connection and may beeasily de-attached or disassembled. Alternatively and additionally, theflame arrester element in a flame arrester according to the presentinvention may be removed from the bottom.

A further aspect of the invention provides a method of altering thepressure of fluid in a first conduit, the method comprising eithercausing a valve means or valve set to open in response to the pressureof fluid in the first conduit being less than a first pressure andallowing a flow of fluid through a flame arrester element extendingabout or around the first conduit, the flow of fluid passing into ahousing, through the open valve means or valve set and thence into thefirst conduit or the method comprising causing a valve means or valveset to open in response to the pressure of fluid in the first conduitbeing greater than the first pressure and allowing a flow of the fluidto travel from the first conduit, through the open valve means or valveset and thence through a flame arrester element extending about oraround the first conduit.

The flow of fluid through the flame arrester element may have aprincipal flow axis. The flow of fluid into the first conduit may have aprincipal flow axis. The principal flow axes may be in oppositedirections, e.g. substantially opposite directions.

For the avoidance of doubt, any of the features described herein applyequally to any aspect of the invention. It will be appreciated that anyof the features specified in relation to one aspect may be used inrelation of the or any of the other aspects of the invention.

Embodiments of the invention will now be described by way of exampleonly with reference to the accompanying drawings in which:

FIG. 1 is a sectional view of a generalised embodiment of a valveapparatus according to the invention;

FIG. 2 is a sectional view of a generalised embodiment of a valveapparatus integrated with a flame arrester according to a furtherembodiment of the invention;

FIG. 3 is a sectional view of a valve apparatus integrated with a flamearrester according to a further embodiment of the invention;

FIG. 4 is a cut-away view of the valve apparatus shown in FIG. 3;

FIG. 5 is a sectional view of the valve apparatus of FIG. 3 with thepressure relief valve in an open condition;

FIG. 6 is a sectional view of the valve apparatus of FIG. 3 with thevacuum relief valve in an open condition;

FIG. 7 is a sectional view of a valve apparatus integrated with a flamearrester according to a further embodiment of the invention;

FIG. 8 is a cut-away view of the valve apparatus shown in FIG. 7;

FIG. 9 is a sectional view of the valve apparatus shown in FIG. 7 withthe pressure relief valve in an open condition;

FIG. 10 is a sectional view of the valve apparatus shown in FIG. 7 withthe vacuum relief valve in an open condition;

FIG. 11 is a sectional view of a valve apparatus integrated with a flamearrester according to a further embodiment of the invention;

FIG. 12 is a perspective view of the valve apparatus shown in FIG. 11with a flame arrester element attached thereto;

FIG. 13 is a sectional view of the valve apparatus shown in FIG. 11 withthe pressure relief valve in an open condition;

FIG. 14 is a sectional view of the valve apparatus shown in FIG. 11 withthe vacuum relief valve in an open condition;

FIG. 15 is a sectional view of a valve apparatus integrated with a flamearrester according to a further embodiment of the invention;

FIG. 16 is a perspective view of the valve apparatus shown in FIG. 15with a flame arrester element attached thereto;

FIG. 17 is a sectional view of the valve apparatus shown in FIG. 15 withthe pressure relief valve in an open condition;

FIG. 18 is a sectional view of the valve apparatus shown in FIG. 15 withthe vacuum relief valve in an open condition; and

FIG. 19 is sectional view of a valve apparatus integrated with a flamearrester according to a further embodiment of the invention.

Referring now to FIG. 1, there is shown a generalised embodiment of avalve apparatus 71 according to a first embodiment of the invention. Thevalve apparatus 71 includes a housing 72, a first, pressure relief valve74, a second, vacuum relief valve 75, a first conduit 76 for fluid flowand a second conduit 77 for fluid flow (which is defined between thehousing 72 and the first conduit 76 in this embodiment). In embodiments,however, the second conduit 77 may not be defined at all by the firstconduit 76.

The housing 72 includes an end wall 720 and a side wall 721 extendingfrom around the periphery of the end wall 720. The end wall 720 and sidewall 721 are joined in a fluid tight manner. The housing 72 is formedfrom cast iron or steel or other suitable alloys, in this embodiment,and may be an integral unit or may include plural components fixedtogether (e.g. by suitable fixing means or fixings such as bolts,welding, etc.). Where the housing 72 includes plural components it willbe understood that they are joined together, prior to use, in a fluidtight manner suitable to retain fluids at the desired operatingpressures (the joins may comprise one or more seals, for example).

The first, pressure relief valve 74 and the second, vacuum relief valve75 are located within the housing 72, e.g. such that the housing 72 isconfigured to cover the valves 74, 75, in use.

The first, pressure relief and second, vacuum relief valves 74, 75 areconfigured to allow a flow of fluid, in use, from the first conduit 76into the second conduit 77 (e.g. which is defined within the housing 72)when the pressure in the first conduit 76 is greater than a firstpressure. The first, pressure relief and second, vacuum relief valves74, 75 are also configured to allow a flow of fluid, in use, from thesecond conduit 77 (e.g. which is defined within the housing 72) into thefirst conduit 76 when the pressure in the first conduit 76 is less thana second pressure. The second pressure is less than the first pressure.The first conduit 76 has a substantially constant cross-section along atleast a portion of its length, in this embodiment, however in otherembodiments the cross-section may vary along at least a portion of thelength of the first conduit 76. The cross-section may have any suitableshape, for example a circle, oval, ellipse, rectangle, etc. The firstconduit 76 is formed from cast iron, steel or aluminium in thisembodiment, however one skilled in the art will appreciate that othermaterials and methods of manufacture may also be suitable.

The first conduit 76 includes a first end 76 a and a second end 76 b.The first end 76 a provides an inlet to the valve apparatus 71 in anout-breathing operation, and in the alterative, in an in-breathingoperation, the first end 76 a provides an outlet from the valveapparatus 71. The first conduit 76 includes an extension 760 whichextends from and is provided at the second end 76 b of the first conduit76. The first, pressure relief valve 74 and second, vacuum relief valve75 are operably connected or secured to the extension 760. The first,pressure relief valve 74 and second, vacuum relief valve 75 are distinctfrom one another.

The first conduit 76 has a principal flow axis A extending therealongfor the flow of fluid, in use, into or out of the valve apparatus 71.The second conduit 77 has a principal flow axis B, for the flow offluid, in use, out of or in to the valve apparatus 71. The principalflow axes A, B are parallel and extend in opposite directions. Thesecond conduit 77 has an open end 77 a for the flow of fluidtherethrough.

In use, the valve apparatus 71 is installed or attached to a site ofuse, for example a tank (not shown) or pipe (not shown) containing orfor containing a fluid (e.g. a combustible or non-combustible fluid).The first end 76 a of the first conduit 76 is attached via attachmentflanges 78 b to a connection (not shown) of the tank or pipe in order toafford fluid communication therebetween. The housing 72 may be connectedto a flame arrester element (not shown) and/or a bird screen (not shown)via attachment flanges 78 a. Attachment may be affected by bolts or anyother suitable means of attachment.

If a pressure of fluid within the first conduit 76 is greater than thefirst pressure then the first, pressure relief valve 74 is caused toopen and allow a flow of said fluid from the first conduit 76 to thesecond conduit 77. The flow of fluid travels from the first conduit 76into the second conduit 77 and thence out of the housing 72. In this wayan excess pressure within a tank or pipe to which the valve apparatus 71is attached may be relieved, e.g. the pressure of fluid within the tankor pipe may be reduced such that it is less than the first pressure.

If a pressure of fluid within the first conduit 76 is less than thesecond pressure then the second, vacuum relief valve 75 is caused toopen and allow a flow of fluid into the first conduit 76. The flow offluid flows from external to the housing 72 (e.g. from the environmentthereabout), through the second conduit 77, through the open second,vacuum relief valve 75 and thence into the first conduit 76. The flowthrough the second conduit 77 defines an annular flow of fluid aroundthe first conduit 76. In this way an excess vacuum within the tank orpipe to which the valve apparatus 71 is attached may be relieved, e.g.the pressure of fluid within the tank or pipe may be increased such thatit is greater than the second pressure.

The pressure of fluid within a tank or pipe to which the valve apparatus71 is attached may therefore be maintained at a level within operatingsafety limits of those structures.

At its open end 77 a the second conduit 77 has a total cross-sectionalarea of flow (e.g. an annular cross-sectional area) which is preferably,but not limited to, between about 1.5 and about 3 times thecross-sectional area of the first conduit 76 at its first end 76 a. Inembodiments the total cross-sectional area of flow of the open end 77 aof the second conduit 77 may be 6 times or more the cross-sectional areaof the first conduit 76 at its first end 76 a, for example up to 16times the cross-sectional area of the first conduit 76 at its first end76 a.

Referring now to FIG. 2, there is shown a generalised embodiment of avalve apparatus integrated with a flame arrester 1 (hereinafter referredto as a valve apparatus 1) according to a further embodiment of theinvention. The valve apparatus 1 includes a housing 2, a flame arresterelement 3, a pressure relief valve 4, a vacuum relief valve 5, a firstconduit 6 for fluid flow and a second conduit 7 for fluid flow (which isdefined between the housing 2 and the first conduit 6 in thisembodiment). The first conduit 6 extends into the housing 2 and theflame arrester element 3 completely surrounds the first conduit 6. Inembodiments the flame arrester element 3 may only partially surround thefirst conduit 6. Where the valve apparatus 1 is described as beingintegrated with a flame arrester it will be appreciated that the flamearrester (for example the flame arrester element 3) may be removably ornon-removably attached to the valve apparatus 1.

The flame arrester element 3, in this embodiment, comprises a crimpedribbon, however in other embodiments it may additionally oralternatively include wire mesh and/or one or more apertured orperforated plates. The flame arrester element 3 has a first majorsurface 300 and a second major surface 301.

The flame arrester element 3 extends from the first conduit 6 to thehousing 2. The flame arrester element 3 extends radially from the firstconduit 6, and concentrically thereabout. The flame arrester element 3is located substantially symmetrically, e.g. symmetrically, around thefirst conduit 6.

The flame arrester element 3 radiates away from the first conduit 6orthogonally (for example substantially orthogonally) to the principalaxis A of the first conduit 6. However, in embodiments the flamearrester element 3 may radiate away from the first conduit 6 at an angleto the principal axis A, for example at an angle less than 90°. In thisembodiment the first and second major surfaces 300, 301 of the flamearrester element 3 are substantially orthogonal to the principal flowaxis A extending along the first conduit 6.

The housing 2 includes an interior chamber 22 between the end wall 20and the flame arrester element 3. In embodiments, the housing 2 maycomprise an upper and a lower portion, for example which may beremovably attached to one another by attachments (not shown). The valveapparatus 1 may comprise the upper portion of the housing 2 whilst theflame arrester element 3 may be located or locatable within the lowerportion of the housing 2. Additionally or alternatively, the firstconduit 6 may comprise an upper portion (for example including thesecond end 6 b) and a lower portion (for example including the first end6 a), where the upper and lower portions may be removably attached toone another by attachments (not shown). The valve apparatus 1 maycomprise the upper portion of the first conduit 6 whilst the flamearrester element 3 may be located or locatable around the lower portionof the first conduit 6. Alternatively, the flame arrester element 3 maybe removably attached to the housing 2 which may comprise a singleportion and/or to the first conduit 6 which may comprise a unitary body.

In use, the valve apparatus 1 functions in an analogous manner to thevalve apparatus 71 shown in FIG. 1. Additionally, the flame arresterelement 3 provides protection against the transmission of atmosphericdeflagration in the vicinity of the flame arrester to a tank or pipe towhich it is connected. The second conduit 7 passes through the flamearrester element 3. Consequently, in use, fluid flow through the secondconduit 7 travels through the flame arrester element 3, either in anin-breathing mode (when the valve apparatus 1 allows fluid flow from thesecond conduit 7 to the first conduit 6) or out-breathing mode (when thevalve apparatus 1 allows fluid flow from the first conduit 6 to thesecond conduit 7). Accordingly, the flame arrester element 3 mitigatesagainst the transmission of deflagrations from outside the valveapparatus 1 to the tank or pipe to which it is attached (not shown).

Referring now to FIGS. 3 to 6, there is shown a valve apparatusintegrated with a flame arrester 11 (hereinafter referred to as a valveapparatus 11) according to a further embodiment of the invention,wherein like features to those described in respect of the valveapparatus 1 shown in FIG. 2 are denoted by like references preceded by a‘1’, which will not be described further herein.

The flame arrester element 13 is removably attached to the housing 12and/or the first conduit 16 by fixings 18 a which are bolts and nuts inthis embodiment. The flame arrester element 13 is a crimped ribbonelement in this embodiment and includes a top element ring 13 a. Inembodiments, however, the top element ring 13 a may not be providedand/or the flame arrester element 13 may be of any other suitable type,for example comprising apertured or perforated plates.

The extension 160 and the conduit 16 are formed from separate parts inthis embodiment and are attached together with a gasket G or O-ringtherebetween. Advantageously, the extension 160 and the conduit 16 maytherefore be readily attached together and/or separated, for example inorder to facilitate inspection and/or removal of the flame arresterelement 13 when necessary. In embodiments the flame arrester element 13may be attached (e.g. removably) to the valve apparatus 11 by analternative arrangement, for example via flanges.

The extension 160 of the first conduit 16 includes a first extension 161with a second extension 162 extending therefrom. The second extension162 has a greater internal diameter than does the first extension 161.The second extension 162 extends from an outer surface of the firstextension 161 and around the entire periphery thereof providing a fluidtight seal therearound. The second extension 162 may be formedintegrally with the first extension 161 or may be attached thereto, forexample welded thereto. The first extension 161 includes a firstextension wall with a passageway 161 a therethrough. The secondextension 162 includes a second extension wall with a passageway 162 atherethrough. In this embodiment component parts such as 12, 160, 161,162, 190 are separate components which are attached together. Inembodiments, however, some or all of the components 12, 160, 161, 162,190 may be formed as a unitary structure, for example by casting. Forexample, the first conduit 16 and the extension 160 may comprise aunitary or permanently joined structure.

The valve apparatus 11 includes a partition or wall VB and a bypassconduit 108.

The partition or wall VB extends between the second extension 162 of thefirst conduit 16 and the housing 12. The partition or wall VB extendsaround the periphery of the extension 162 and provides a fluid tightseal between the housing 12 and the second extension 162. A firstchamber C1 is defined between the end wall 120 of the housing 12 and thepartition or wall VB.

The bypass conduit 108 is located within the housing 12 and isconfigured to allow, in use, fluid communication between the firstconduit 16 and the first chamber C1 when either or both of the first,pressure relief valve 14 and the second, vacuum relief valve 15 are in aclosed or open position or condition. In this way the bypass conduit 108is configured to provide a bypass route for fluid flow past the valveapparatus 11 to and from the first chamber C1.

The bypass conduit 108 includes a diversion barrier or wall 190 whichextends from the extension 160 to the housing 12. The bypass conduit 108is thus defined by a portion of the housing 12, a portion of theextension 160, a portion of the second extension 162, the partition orwall VB, the diversion barrier or wall 190 and two diversion walls 190 awhich extend between extension 160, the second extension 162 and thehousing 12. The diversion barrier or wall 190 forms a fluid tight sealwith the first extension 161 and the side wall 121 of the housing 12.The diversion walls 190 a extend from the first and second extensions161, 162 to the side wall 121 of the housing 12 and provide a fluidtight seal against the first and second extensions 161, 162, the sidewall 121 of the housing 12, the diversion barrier or wall 190 and thepartition or wall VB. The partition or wall VB includes a passageway VB1therethrough, positioned to allow fluid communication between the firstchamber C1 and the bypass conduit 108.

The first, pressure relief valve 14 is mounted to the first extension161 and the second, vacuum relief valve 15 is mounted to the secondextension 162. The first, pressure relief valve 14 includes a firstvalve pallet 14 a and a first valve seat 14 b. The first valve seat 14 bis disposed at the end of the first extension 161. The second, vacuumrelief valve 15 includes a second valve pallet 15 a and a second valveseat 15 b. The second valve seat 15 b is located at the end of thesecond extension 162. The first and second valves 14, 15 are paralleland spaced from one another and are concentrically aligned about centralaxes through each valve 14, 15.

In the valve apparatus 11 shown in FIGS. 3 and 4 the first, pressurerelief valve 14 and the second, vacuum relief valve 15 are both biasedtoward a closed condition or position by a mass m attached to each ofthe first and second valve pallets 14 a, 15 a (and are absentcompression springs or other forms of resilient biasing means orresilient biasing members).

The valve apparatus 11 also includes first and second guides 109, 110(which are stem guides in this embodiment) configured to guide,respectively, in use, the first, pressure relief valve 14 and thesecond, vacuum relief valve 15. The first guide 109 includes a firststem 109 a, having a first end attached to the second valve pallet 15 aand a second, free end, received within a first cylinder 109 b. Thefirst cylinder 109 b is attached to the end wall 120 of the housing 12.The second guide 110 includes a second stem 110 a, having a first endattached to the first valve pallet 14 a and a second, free end, receivedwithin a second cylinder 110 b. The second cylinder 110 b is attached tothe extension 160 by arms.

It will be appreciated by one skilled in the art that differentstructures of first and second guides may be used, for example, those asshown in the second, vacuum relief valve (FIG. 3).

The end wall 120 of the housing 12 is removably attached thereto byfixings 8 c, which are bolts and nuts in this embodiment, although inembodiments the fixings 8 c may be of any suitable type. Advantageously,by removing the end wall 120 the second vacuum relief valve 15 may beinspected and/or removed for repair or replacement readily and rapidly.If the second, vacuum relief valve 15 is removed the first, pressurerelief valve 14 may be inspected and/or removed for repair orreplacement.

The end wall 120 of the housing 12 is shown as having a generally flatouter surface in this embodiment, however, in embodiments this need notbe the case and instead the end wall 120 may have any suitable shape.For example, the end wall may have a convex or concave (dished) shape).The first guide 109 may at least partially extend beyond part or themajority of the outer surface of the end wall 120. Advantageously, theoverall volume of the valve apparatus 11 may be relatively reduced bythis arrangement, with a consequential saving in material use and henceweight and expense. In embodiments the end wall 120 may comprise alifting eye or lug or a ring nut or other attachment.

In use, if the pressure of fluid within the first conduit 16 exceeds thefirst pressure, the first, pressure relief valve 14 is caused to moveinto an open position or condition, whereby the first valve pallet 14 ais caused to move away from the first valve seat 14 b against the biasof the mass (as shown in FIG. 5). Fluid is then allowed to flow from thefirst conduit 16 into the second extension 162 and thence through thepassageway 162 a therein and out of the second conduit 17 and hence outof the housing 12. It will be appreciated by one skilled in the art thatflow through the second conduit 17 will surround the first conduit 16,whilst the arrows are provided merely to indicate the direction of flow.When the pressure of fluid within the first conduit 16 is reduced to apressure less than the first pressure, the first, pressure relief valve14 returns to the closed position or condition due to the biasing actionof the mass m.

If the pressure of fluid within the first conduit 16 is less than thesecond pressure (e.g. an excess vacuum is present), the second, vacuumrelief valve 15 is caused to move into an open position or condition (asshown in FIG. 6). Reduced pressure (e.g. excess vacuum) of fluid withinthe first conduit 16 is transmitted to the first chamber C1 via thebypass conduit 108 (e.g. fluid within the first chamber C1 flows fromthe first chamber C1 to the first conduit 16 via the bypass conduit108). The relatively reduced pressure within the first chamber C1 isconfigured to overcome the bias of the mass m attached to the secondvalve pallet 15 a when the pressure in the first conduit 16 is less thanthe second pressure causing the second valve pallet 15 a to unseat fromthe second valve seat 15 b and hence move into an open position orcondition. Fluid is then allowed to flow (as indicated by the arrows inFIG. 6) from external to the housing 12, through the second conduit 17,through passageway 162 a in the second extension 162, into the firstchamber C1 through the open second, vacuum relief valve 15 and thence tothe first conduit 16 via the bypass conduit 108. It will be appreciatedby one skilled in the art that flow through the second conduit 17 willsurround the first conduit 16, whilst the arrows are provided merely toindicate the direction of flow. When the pressure of fluid within thefirst conduit 16 has increased to a pressure greater than the secondpressure, the second, vacuum relief valve 15 returns to the closedposition or condition, biased by the mass m attached to the second valvepallet 15 a.

Advantageously, the end wall 120 of the housing 12 has a larger diameterthan do the pallets 14 a, 15 a of the pressure and vacuum relief valves14, 15, enabling ready access to said valves 14, 15. Furthermore, thepallet 14 a which is located furthest from the housing 12 end wall 120(which is the pressure pallet 14 a in this embodiment) has a smallerdiameter than does the valve 15 which is relatively nearer to thehousing 12 end wall 120.

In this way, the valve furthest from the end wall 120 of the housing 12may be more readily and rapidly inspected and/or removed for repair orreplacement.

In embodiments, the end wall 120 or portion, for example an openable endwall or portion (not shown) will automatically open as a pressure in thefirst conduit 16 reaches a pre-determined value or dangerous level forexample due to valve malfunctions or due to the blockage of flamearrester element or in an emergency case. Advantageously, the valveapparatus may operate as an emergency vent or emergency pressure reliefdevice/valve to protect equipment, storage tanks or containers fromoverpressure damage.

The second conduit 17 and/or the housing 12 may comprise in-situcleaning means e.g. a cleaning nozzle (not shown). Cleaning nozzles maybe distributed (each at same or different angles and at distinctlocations) on a wall of the second conduit 17 and/or the housing 12.Nozzles preferably located above the flame arrester element 13 at a siteof use may be arranged to discharge a cleaning liquid or compressed gas.A cleaning liquid will clean the flame arrester element.

Advantageously, in-situ cleaning means/nozzles enhance useful anduseable lifetime or maintenance interval of the flame arrester.Accordingly the valve apparatus will reliably function under operatingconditions and work efficiently with a less maintenance frequency. Inembodiments, the flame arrester element 13 may extend only partiallyaround the first conduit 16. In embodiments the flame arrester element13 may extend around the first conduit in a plane perpendicular to theprincipal flow axis of the first conduit 16, for example in a plane inwhich the bypass conduit 108 (e.g. a lower portion thereof, where loweris relative to the orientation shown in FIG. 3) is located. Inembodiments, the flame arrester element 13 and the diversion barrier orwall 190 may extend around the first conduit in a plane perpendicular tothe principal flow axis of the first conduit 16. In the planeperpendicular to the principal flow axis of the first conduit 16 thearea (i.e. the annulus as shown) between the first conduit 16 and thehousing 12 may be provided (for example over all of its area) with thebypass conduit 108 and the flame arrester element 13. In embodiments,the flame arrester element 13 may extend around the first conduitbetween diversion walls 190 a, for example around the portion of thecircumference of the first conduit not configured to provide the bypassconduit 108. In embodiments, the flame arrester element may comprise aperforated plate.

Referring now to FIGS. 7 to 10, there is shown a valve apparatusintegrated with a flame arrester 21 (hereinafter referred to as a valveapparatus 21) according to a further embodiment of the invention,wherein like features to those described in respect of the valveapparatus 1 shown in FIG. 2 are denoted by like references preceded by a‘2’, which will not be described further herein. The valve apparatus 21differs from the valve apparatus 11 shown in FIGS. 3 to 6 in that thereare two separate pathways in either an in-breathing or an out-breathingmode for the flow of fluid between the first and second conduits 26, 27.The valve apparatus 21 includes first 262 a and second (not shown)passageways through the second extension wall 262 and first and secondbypass conduits 208 a, 208 b defined between first and secondpassageways VB1, VB2 through the partition or wall VB and, respectively,first and second passageways 261 a, 261 b through the first extensionwall 261.

In an out-breathing mode, when the first, pressure relief valve 24 iscaused to move into an open condition (as shown in FIG. 9), fluid flowsfrom first conduit 26 through the open pressure relief valve 24, throughthe first and second passageways 262 a and thence to the second conduit27. In an in-breathing mode, when the second, vacuum relief valve 25 iscaused to move into an open condition (as shown in FIG. 10), fluid flowsfrom the second conduit 27 to the vacuum relief valve 25 through thefirst and second passageways 262 a (see FIG. 8), through the vacuumrelief valve 25 and to the first conduit 26 by way of first and secondbypass conduits 208 a, 208 b and the first and second passageways 261 a,261 b. In this embodiment the flow of fluids within the valve apparatus21 is well distributed and thus the flow capacity is relatively improvedwith respect to prior art apparatus.

Referring now to FIGS. 11 to 14, there is shown a valve apparatusintegrated with a flame arrester 31 (hereinafter referred to as a valveapparatus 31) according to a further embodiment of the invention,wherein like features to those described in respect of the valveapparatus 1 shown in FIG. 2 are denoted by like references preceded by a‘3’, which will not be described further herein. The valve apparatus 31differs from the valve apparatus 11 shown in FIGS. 3 to 6 in that thepressure relief valve 34 is positioned nearer to the end wall 320 of thehousing 32 than is the vacuum relief valve 35. To accommodate thisarrangement the second extension 362 extends within the first extension361. The valve apparatus 31 functions in a comparable manner to thevalve apparatus 11 shown in FIGS. 3 to 6. It will be appreciated by oneskilled in the art that flow through the second conduit 37 will surroundthe first conduit 36, whilst the arrows are provided merely to indicatethe direction of flow.

Referring now to FIGS. 15 to 18, there is shown a valve apparatusintegrated with a flame arrester 41 (hereinafter referred to as a valveapparatus 41) according to a further embodiment of the invention,wherein like features to those described in respect of the valveapparatus 1 shown in FIG. 2 are denoted by like references preceded by a‘4’, which will not be described further herein. The valve apparatus 41differs from the valve apparatus 31 shown in FIGS. 11 to 14 in thatthere are plural vacuum relief valves 45. The second extension 462comprises two separate chambers which extend outwardly with respect tothe first extension 461 and the first conduit 46. A vacuum relief valve45 is provided in each of the separate chambers of the second extension462. Furthermore, parts 462 d of the end wall 462 c of the secondextension 462 (beneath which the vacuum relief valves 45 are located)are removably attached to the remainder of the end wall 462 c (e.g. bybolts or other fixings). Advantageously, this embodiment is relativelysimple in comparison to the other embodiments and may accordingly bemore readily and rapidly installed and/or removed from a site of use.Where the housing 42 is provided by a pre-existing structure the valves44, 45 may be removed or installed within the housing 42 more readilyand rapidly.

In use, the valve apparatus 41 functions in an analogous manner to thevalve apparatus 11 shown in FIGS. 3 to 6. Advantageously, if one of thevacuum relief valves 45 becomes stuck or its functioning is otherwiseimpaired the remaining vacuum relief valves 45 may continue to functionand hence continue to provide vacuum relief, when needed. Accordingly,the plural vacuum relief valves 45 provide redundancy in case of failureor impaired functioning of other vacuum relief valves 45. Furthermore,the provision of plural vacuum relief valves 45 relatively improves thevacuum flow capacity of the valve apparatus 41. Furthermore, the flowcapacity for each of pressure relief and vacuum relief is different inthe present embodiment. As will be appreciated by one skilled in the artthe total flow through area of the vacuum relief valves relative to thetotal flow through area of the pressure relief valve may be selectedaccording to the application to which the valve apparatus 41 is intendedfor use. Accordingly, the number of and/or flow through area of one ormore of the vacuum relief valves 45 may be altered dependent on thedesired vacuum relief and venting requirements.

By removably attaching parts 462 d of the end wall 462 c of the secondextension 462 it is possible to readily and rapidly remove one or moreof the vacuum relief valves 45 or to inspect said one or more vacuumrelief valves 45.

In embodiments there may be only one vacuum relief valve 45 or there maybe more than two vacuum relief valves, for example 3, 4, 5 or anysuitable number. In embodiments the second extension 462 may comprise asingle vacuum chamber, for example which may extend around the peripheryof the second extension. In embodiments one or more of the plural vacuumrelief valves 45 may have a different second pressure to the other valveor valves 45, for example the mass m may be different and/or the surfacearea of the valve pallet may be different. In this way one or morevacuum relief valve 45 may open once an initial second pressure has beenreached, whilst one or more other vacuum relief valves may open once afurther second pressure has been reached.

It will be appreciated by one skilled in the art that the vacuum reliefvalve 45 may be in a form of one single annular ring. That is, thepallet and seat of the vacuum relief valve 45 is in a form of annularring.

Referring now to FIG. 19, there is shown a valve apparatus integratedwith a flame arrester 801 (hereinafter referred to as a valve apparatus801) according to a further embodiment of the invention, wherein likefeatures to those described in respect of the valve apparatus 1 shown inFIG. 2 are denoted by like references preceded by an “80′, which willnot be described further herein. The valve apparatus 801 shown in FIG.19 differs from that shown in FIG. 2 in that the flame arrester element803 extends radially from the first conduit 806 in an eccentric orasymmetric manner (e.g. the first conduit 806 is located eccentricallywithin the housing 802).

It will be appreciated by those skilled in the art that severalvariations to the aforementioned embodiments are envisaged withoutdeparting from the scope of the invention. For example, although valveapparatus 1, 11, 21, 31, 41, 801 are described as including a flamearrester element this need not be the case and instead they may beabsent a flame arrester element. Where a valve apparatus without a flamearrester element is provided the first conduit and extension maycomprise a unitary structure and/or may be relatively reduced in size,e.g. in length or height. Additionally or alternatively, the housing maybe relatively reduced in size, e.g. in length or height. Additionally oralternatively, a fluid permeable screen or barrier may be providedbetween the first conduit and the housing, for preventing the ingress ofobjects or organic matter (such as birds and insects) into the valveapparatus.

Additionally or alternatively, the housing of any of the above describedvalve apparatus may have any suitable shape. Additionally oralternatively, the guides of the first, pressure relief valve or thesecond, vacuum relief valve of any of the above described valveapparatus may include a cylinder attached to the valve and a stemattached to the housing or a biasing plate. Additionally oralternatively, more than one guide may be provided on one or each valve,for example 2, 3 or 4 guides. Additionally or alternatively, any of thevalve apparatus may include pressure and/or vacuum relief valves whichare biased by a mass and/or one or more spring, for example biasedtoward a closed condition or position. Additionally or alternatively,any of the above described valve apparatus may comprise an air cushionseal with a diaphragm for providing a fluid tight seal between the valvepallet and valve seat of one or both of the valves.

Any or all of the valve apparatus described above may be provide with ahousing which comprises a removable cover, for example for maintenancepurposes. Additionally or alternatively one or more of the valveapparatus may comprise one or more of a solids trap, for example toremove entrained solid particulates from a gas or vapour flow, a liquiddrain, for example to remove entrained liquids from a gas or vapourflow, cleaning means, for examples nozzles arranged, preferably, toperiodically discharge, e.g. to force, a cleaning medium into thehousing.

It will also be appreciated by those skilled in the art that any numberof combinations of the aforementioned features and/or those shown in theappended drawings provide clear advantages over the prior art and aretherefore within the scope of the invention described herein.

1-26. (canceled)
 27. A valve apparatus for connection to a tank or pipe,the valve apparatus comprising a housing, a first opening and a secondopening communicating with respective first and second conduits each forproviding ingress and egress of fluid into and out of the housingthrough the first opening and the second opening, and discrete first andsecond valves which are spaced apart from one another, the first andsecond valves selectively controlling fluid flow between the first andsecond conduits, wherein, in use, the principal flow axes along thefirst conduit and second conduit are parallel and opposed, the firstvalve is configured to open when the pressure in the first conduit isgreater than a first pressure and the second valve is configured to openwhen the pressure in the first conduit is less than the first pressure.28. The valve apparatus according to claim 27, wherein the first andsecond valves are vertically and/or horizontally spaced apart from oneanother.
 29. The valve apparatus according to claim 27, wherein thesecond conduit surrounds the first conduit.
 30. The valve apparatusaccording to claim 29, wherein the first and second conduits arecoaxial.
 31. The valve apparatus according to claim 27, wherein thesecond conduit is defined between the first conduit and the housing. 32.The valve apparatus according to claim 27, wherein the first valvecomprises a first valve plate or pallet and the second valve comprises asecond valve plate or pallet, the first valve plate or pallet and thesecond valve plate or pallet extending in the same plane orsubstantially parallel to one another.
 33. The valve apparatus accordingto claim 32, wherein the first valve plate or pallet and the secondvalve plate or pallet are horizontally displaced from one another. 34.The valve apparatus according to claim 27, comprising a diversionbarrier or wall extending between the first conduit and the housing andconfigured to occlude a portion of the second conduit.
 35. The valveapparatus according to claim 34, wherein the diversion barrier providesat least part of a diversion path for fluid flowing from the firstopening to the second opening or from the second opening to the firstopening.
 36. The valve apparatus according to claim 27, wherein thefirst conduit has a second end, and further comprising an extensionextending from the second end of the first conduit.
 37. The valveapparatus according to claim 36, wherein the extension is configured todefine a flow path between the first conduit and one of the first andsecond valves, where the flow path bypasses the other of the first andsecond valve.
 38. The valve apparatus according to claim 27, wherein theflow path between the first opening and the second opening is longer inout-breathing mode than in in-breathing mode or is shorter inout-breathing mode than in in-breathing mode.
 39. The valve apparatusaccording to claim 27, wherein the first and second valves areconfigured to be biased in use toward a closed position or condition bya respective resilient biaser.
 40. The valve apparatus according toclaim 27, comprising one or more of: a solids trap; a liquid drain;cleaning means.
 41. The valve apparatus according to claim 27, wherein aor the end wall of the housing is openable to provide an emergencyrelief vent.
 42. The valve apparatus according to claim 27, comprising aflame arrester element.
 43. The valve apparatus according to claim 42,wherein the flame arrester element is located at least partially in oradjacent the second conduit.
 44. The valve apparatus according to claim42, wherein the flame arrester element surrounds the first conduit. 45.The valve apparatus according claim 42, wherein the flame arresterelement extends radially from the first conduit.
 46. The valve apparatusaccording to claim 42, wherein the flame arrester element is locatedsubstantially symmetrically or asymmetrically around the first conduit.